Experimental study on dynamic properties and constitutive model of polypropylene fibre concrete under high-strain rates

An improved Split Hopkinson pressure bar (SHPB) test device was used to study the dynamic characteristics and the constitutive relationships of polypropylene fibre-reinforced concrete (PFRC). The uniaxial SHPB impact experiments of PFRC with five fibre contents under different strain rates were conducted. The effects of strain rates and fibre contents on concrete strength and toughness were then analysed according to the experimental stress-strain curves. The constitutive model of PFRC was obtained according to the damage viscoelastic constitutive model and fitting of test data. Experimental results show that PFRC has non-linear properties and is sensitive to strain rates under impact loads. Dynamic strength and toughness of PFRC grow non-linearly following a parabolic trend as the fibre contents increasing. The dynamic stress-strain relationship of PFRC can be well described by the damage viscoelastic constitutive model in this paper.